Patent GB-819489-A (GB)
Title: Improvements in differentially connected twin turbine power plant
IPC: F02C7/36
Filed: 1956-05-25
Abstract: 819,489. Gas turbine driven vehicles. HUTCHINSON, D. W. May 25, 1956 [May 25, 1955], No. 16256/56. Classes 79(1), 79(2) and 79(3) [Also in Groups XXVI and XXXIII] A gas turbine power plant for driving a road vehicle, locomotive or ships propeller comprises a pair of gas turbines each of which has a drive shaft connected to compression means the discharge from which is heated and supplied to the turbines and differential gearing connecting the two turbine drive shafts and an output shaft whereby one drive shaft provides power to drive the output shaft and assists the other drive shaft to drive its compression means. The gas turbine power plant, Fig. 1, comprises a pair of gas turbine plants which drive locomotive wheels 60 through a differential gear 42, 44, 52 and a power shaft 58. One gas turbine plant comprises a compressor 4 the discharge of which is heated in an exhaust gas heat exchanger 14 before being further heated in a combustion chamber 18 feeding a turbine 6 driving the compressor. The fuel supply to the combustion chamber 18 is controlled by a fuel metering speed governor 70 having a speed control lever 82. The other gas turbine plant is identical and comprises a compressor 24. heat exchanger 34, combustion chamber 38, turbine 26, speed governor 90 and speed control lever 100. The gas turbine drive shafts 2, 22 are connected respectively to bevel gears 42, 44 which mesh with a pair of bevel gears 52 carrying a gear 54 driving the locomotive wheels 60 through gears 56, 62, 64. The output shaft 58 may be made to rotate in one direction or the other or to remain stationary by controlling the relative speeds of the turbine drive shafts 2, 22 through the control levers 82, 100. If it is desired to control output torque instead of output speed only one of the governors 70, 90 needs to be operated at a time and the fuel supply to the other governor shut off. Means are also described for operating the control levers 82, 100 from a single control lever. In a modification, the compressed air from the compressor 4 and heat exchanger 14 is fed to the combustion chamber 38 and the compressed air from the compressor 24 and heat exchanger 34 is fed to the combustion chamber 18. The exhausts from the turbines 6, 26 may pass into either heat exchanger. In a further modification, Fig. 2 (not shown) the compressors 24, 4 and turbines 6, 26 are arranged in series to form a two shaft compound gas turbine plant with a reheat combustion chamber between the turbines. The differential gearing arranged between the two shafts is such that when the output shaft 58 is stationary the two shafts run at unequal speeds. This plant may be started by driving one or both of the shafts by means of an electric or air motor and run up to speed with shaft 58 stationary by suitably controlling the speeds of the two shafts. In another modification, Fig. 3 (not shown), the compressors and turbines are again arranged in series but in this case, the high pressure turbine drives the low pressure compressor and the low pressure turbine the high pressure compressor. An intercooler is arranged between the compressors. In this arrangement the speed governor 70 is used to control variable area nozzles at the inlet of the low pressure turbine. This allows for the elimination of the reheat combustion chamber if desired. Variable area nozzle control may also be provided at the inlet of the high pressure turbine. The compressors and turbines may be of the axial, centrifugal or mixed flow type. If it is desired to provide positive and negative torques at all output speeds one of the governors 70, 90 may be replaced by a manual control so that variation of this control whilst the remaining governor is set at constant speed would vary the output torque. One of the governors may be driven by the output shaft 58.